1. Field of the Invention
The present invention generally relates to a system for latching the fin covers of a missile having retractable folding fins in the stowed position and for releasing and jettisoning the covers to permit deployment of the fins upon command following launch of the missile.
2. Description of the Related Art
Presently existing mechanisms for fin deployment on gun-launched projectiles are both complex and expensive. The requirement to withstand the acceleration forces, which typically range from 10,000 to 30,000 G's, places very stringent demands on the mechanisms. Therefore, the designs are required to be extremely robust in order to withstand the loads induced by these accelerations. It is a purpose of this invention to show a simple but unique configuration that is both low cost to produce and extremely robust. It is particularly capable of withstanding extreme accelerations.
Presently, existing actuators for fin deployment on gun-launched projectiles typically employ multiple pyrotechnics to eject the covers and additional spring-loaded mechanisms to deploy the fins. Typically, each separate cover being jettisoned requires its own pyro device. Such systems also require wires to be connected to each individual pyrotechnic device, thus adding to the cost and complexity of the systems. 
A key objective of the present invention is to be able to withstand the severe accelerations during gun launch and subsequently to function correctly during flight. It is desired to retain the covers over the canard slots throughout the storage life of the round and during the gun launch as well as in the initial portion of the flight. It is then desired to release the covers upon command from the flight control system and eject them in such a way that the covers do not impact any portion of the vehicle, such as the tail fins, as they are jettisoned. Further, at the time the covers are jettisoned the fins are to unfold from within the vehicle and extend into their flight controlling positions in the airstream.
One particular application Ser. No. 09/825,808, entitled FIN AND COVER RELEASE SYSTEM and assigned to the assignee of the present application, describes a system which uses a single electrically initiated pyrotechnic actuator (pyro device) which, upon activation, drives a piston to move a mechanism which first unlatches the covers and then pushes them off, all at the same time. The content of that particular application is incorporated herein by reference, as though set out in haec verba.
There still remains, however, a need to control the deployment of the fins over a wider range of aerodynamic conditions. Such control is needed to avoid excessive fin velocity during deployment which, when the fin is abruptly stopped at its deployed position, might break off the fin support arm or do other structural damage. That problem is met by separate means in each of the two embodiments disclosed herein. 